The Devonian (419-359 million years ago) is the geological period when the terrestrial biota fully established. Early representatives from a terrestrial and continental aquatic biota have previously been reported from the Upper Devonian (Famennian) Strud quarry in Belgium, in the shape of seed-bearing plants and vertebrates (fish and early tetrapods). The palaeoenvironment is interpreted as a floodplain with slow accumulation of sediment in the river channels and adjacent shallow pools, subject to seasonal flooding and desiccation. This thesis presents the upper Famennian Strud ecosystem with representatives from the largest animal phylum – the Arthropoda. Pancrustaceans are dominating the arthropod assemblage by two eumalacostracans (previously described), three groups of branchiopods, and a putative insect, all collected in fine shales likely deposited in the shallow pools. The branchiopods from Strud comprise new members from all three extant clades, i.e. notostracans, anostracans, and spinicaudatan diplostracans. The notostracan Strudops goldenbergi is remarkable for its close resemblance with the extant genus Triops by the overall body plan and telson morphology. A phylogenetic analysis including modern and extinct notostracans and anostracans was performed, where Strudops appears as the earliest undisputed notostracan ever found. In addition, new genera of Anostraca (Haltinnaias serrata) and Spinicaudata (Gesvestheria pernegrei) are described herein. The insect Strudiella devonica consists of a single specimen and is interpreted to have been a nymph due to its minute size and wingless appearance. The chelicerates are represented by one or several species of eurypterids. So far unnamed juvenile eurypterid remains have also been found within the pool strata, and fragments of adult individuals in the coarser river deposits. The branchiopod community displays a unique insight to the ecosystem that these crustaceans inhabited. This is partly because of their co-occurrence, but mainly because they are preserved in close association to draught-resistant encysted eggs, in the same manner as modern day branchiopods do to survive and disperse during periods of drought and freezing. Altogether, the arthropod assemblage offers insight to Late Devonian freshwater ecosystems, and provides further understanding of the evolution of respective groups.

Common heliotrope (Heliotropium europaeum L.) is an herbaceous Mediterranean summer annual that grows on areas devoid of vegetation in the dry-land cropping region located in the north-west of the state of Victoria, Australia. This region is known as the Mallee, and common heliotrope is considered a weed here because it transpires soil water that could otherwise be used by ensuing crops, and is toxic to livestock. / In this study, laboratory experiments have shown that germination of seeds of common heliotrope is not limited by light, cold treatment, or a leacheable inhibitor. Temperature and water potential (and perhaps depth inhibition) are the principal environmental factors that limit germination. Although 100 % of seeds will germinate under optimal conditions, these conditions are rarely met in the field, and the percentage of seeds that germinate at sub-optimal conditions changes seasonally and between Australian populations. This is the principal mechanism of dormancy in the species, ensuring that seeds do not germinate when conditions are unfavourable for continued growth and that in the field, germination of a seed population is fractional, spreading risk temporally. Germination of seeds of common heliotrope does not conform to the assumptions of the hydrothermal time model frequently used to predict field emergence of weed species. / Field observations and simulated rainfall experiments on a consistent soil type (Calcarosol with a clay loam surface texture and clay subsoil) indicated that approximately 20 mm of rainfall is the minimum amount required for germination and emergence of common heliotrope. Field experiments using lysimeters indicated that this is also the amount required for minimal reproduction on the same soil type. Although common heliotrope can successfully reproduce upon the rainfall event which causes its germination, its growth is indeterminate, and further access to moisture will result in massively increased reproductive output. Plants will continue to grow and produce seed over summer until they are killed by drought or senesce in autumn. Laboratory and field studies showed that root growth in common heliotrope is relatively slow, and is opportunistic in areas where moisture becomes available. / Simulation of soil water and temperature fluxes showed that soil type has a large impact on the amount and duration of water potential that seeds and plants are exposed to. In the case of common heliotrope, this is critical in determining regional prevalence and distribution in the north-west of Victoria. It is recommended that studies of arid species reliant on isolated rainfall events for emergence should consider absolute water availability and not in terms of rainfall amount alone. / Analysis of long term summer rainfall data from the Victorian Mallee indicates that there is potential for reducing the cost of controlling common heliotrope by using residual pre-emergent sulfonylurea or triazine herbicides, instead of the traditional post-emergent herbicides or cultivation. More information is needed on the efficacy of such residual herbicides on common heliotrope and other summer weeds, and their impact on subsequent crops before the full potential of this management option is known. Reduced cost of control could also be achieved by economic analysis of the likely benefits of controlling each emerging cohort of common heliotrope, and a framework for decision making is suggested.

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona. / Includes bibliographical references.

Thesis (M.S. - Renewable Natural Resources)--University of Arizona, 1989. / Includes bibliographical references (leaves 139-142).

Thesis (M.S. - Renewable Natural Resources)--University of Arizona, 1989. / Includes bibliographical references (leaves 139-142).

Thesis (M.S. in Meteorology and Physical Oceanography)--Naval Postgraduate School, September 2009. / Thesis Advisor(s): MacMahan, Jamie. "September 2009." Description based on title screen as viewed on 5 November 2009. Author(s) subject terms: Overtopping, run-up, barrier, natural beach, Carmel River Beach Includes bibliographical references (p. 41-44). Also available in print.

No description available.

This research project provides a geomorphological and geological analysis of ephemeral and relict river valley systems in the north part of the Iraqi Western Desert. The area surveyed covers approximately 30 000 km2 and is one of the remotest and least studied parts of the Arabian Peninsula. Part of the reason for the lack of research in this area in recent years has been the ongoing security problems and all fieldwork undertaken for this thesis was carried out with the support of armed guards and police. In addition much of the work on the geology and geomorphology of the region is in confidential files commissioned by oil companies, and in MSc and PhD theses held in Iraqi Universities. A significant part of this work and indeed many scientific papers, are only available in Arabic. Therefore a major element of the work for this thesis has been to translate this material and make the results available in English for the first time. The study demonstrates that the present surface of the Iraqi Western Desert overall forms an incised plateau developed during two phases of continental erosion and deposition during the Tertiary and Quaternary periods. The first phase started after Oligocene uplift formed an older plateau within the Oligocene Tayarat formation. This plateau is characterized by denudation processes associated with a semiarid climate, including the formation of subsurface hollows and caves. The second phase, which began after the last Alpine Orogenic movement, and includes the Pliocene and Quaternary periods, formed a younger plateau developed on the Zahra formation. This younger plateau is characterized by processes indicative of climatic fluctuations from wet to arid and semiarid, which induced denudation in places and deposition in others. However, in terms of the geomorphological landforms present in the Western Desert they can be broadly divided into: i) Structural and erosion-denudation forms ii) Accumulation forms Lithology landform in these two categories has resulted in the production of a new geomorphological map of the Iraqi Western Desert. A key component of this map uses the drainage networks. Four distinct drainage systems were identified: 1. The valleys which descend from west to east. These valley systems are located to the south and south east town of Rutba 2. The valleys which descend from south to north. These lie to the west and southwest of Rutba and are controlled by the north to south strike of exposed Palaeogene strata. 3. The valleys which descend from east south to north west, located north of the Garaa area like Ratga and Akash. 4. The valleys which descend from east to west. These valley systems are located to the south and south west town of Rutba, like Swab and Wallaj valleys. Investigation of these four networks established that they were relict systems that still carried ephemerally active misfit rivers and stream. The overall control on their form was the alternating sequences of variable strength rocks that were exposed and eroded as part of the uplift of an anticlinorium (Houran) and anticline (Garaa), associated with the Alpine Orogeny .However, the unclearing Structures were much older and can be traced back to Permian tectonic processes. The drainage of the Western Desert, therefore, is antecedent and controlled by Tertiary and Quaternary tectonics. The rivers appear to have active throughout the Pleistocene incising into the Western Desert plateaux. Highest incision rates probably occurred during more pluvial periods in the Pleistocene which may have been coincident with glacial marine in the Northern Hemisphere. The contemporary rivers are misfit within larger valleys although still subject to flash floods under the right metrological condition.

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1983. / Includes bibliographical references (leaves 117-120).

Master of Science / Department of Agronomy / Nathan O. Nelson / Phosphorus (P) is an essential nutrient in crop production, but P inputs to surface waters have resulted in impairments such as eutrophication and algae blooms. Non-point sources such as agricultural fields are a main contributor of P. Kansas, being a high agricultural dependent state, has frequent fresh water body impairments. Multiple erosion and transport processes contribute to P loss. While P loss from sheet and rill erosion has been studied extensively, P loss from ephemeral gully erosion is largely unknown. The objective of this study is to understand the effects ephemeral gullies have on the transport and transformation of P. Three fields in McPherson County with well-defined ephemeral gullies were studied. Soil samples were taken in field locations that are effected by ephemeral gullies at the 0 to 2, 2 to 5, 5 to 15, and 15 to 30 cm depths. Samples were analyzed for total P, anion exchange phosphorus (AEP) (labile P), ammonium-oxalate extractable Fe, Al, and P (Fe[subscript]ox, Al[subscript]ox, P[subscript]ox), Mehlich 3 extractable Fe, Al, Ca, and P (Fe[subscript]M3, Al[subscript]M3, Ca[subscript]M3, P[subscript]M3), equilibrium phosphorus concentration at zero net sorption (EPC[subscript]0), 1:1 soil to water pH, and texture. Soil testing showed that P quantities tend to be much higher in surface soils eroded by sheet and rill erosion and lower in subsoil soil that is eroded by ephemeral gullies. The quantity of sorptive elements such as Fe and Al, were not significantly different throughout the tested area except in areas of changing soil texture. EPC[subscript]0 testing showed it was likely that P desorbs from the surface erosion of sheet and rill and is adsorbing onto the subsoil eroded from ephemeral gullies. Sediment eroded by ephemeral gullies has a P buffering capacity greater than the sediment eroded by sheet and rill, and a small quantity of ephemeral gully subsoil will have a large effect on the dissolved P concentration of runoff. Sediment, total P loss and expected dissolved P in runoff was surveyed and modeled for two of the fields. Ephemeral gullies contributed to a majority of sediment and total P loss. The addition of ephemeral gully sediment to the erosional mix of sheet and rill sediment caused the dissolved P concentration to decrease from 0.0204 to 0.0034 mg L[superscript]-1 in one field and from 0.0136 to 0.0126 mg L[superscript]-1 in another. The results of this study show that best management practices (BMPs) such as grass waterways could cause the losses of total P to decrease as much as 2 to 12 times in fields with ephemeral gullies. However, reducing ephemeral gully erosion will likely increase dissolved P concentrations up to 600% more in runoff. Therefore, BMPs need to be combined to fully control P loss from agricultural fields.